The following is a  cross blog post from the U.S. Census Bureau's Random Samplings Blog

Statistics from the American Community Survey show women now lead men in college completion (see Women Now at the Head of the Class, Lead Men in College Attainment). Colleges have been graduating more women than men for more than 20 years, but what is new is that the advantage is no longer limited to new graduates and young women. Counting the entire population 25 and older, even women and men who are retired, women are ahead of men in college graduation. That is to say, the average adult woman in the U.S. is more likely to be a college graduate than the average adult man.

In order to better understand this change, the report “Educational Attainment in the United States: 2015” assembles statistics on historical trends in men’s and women’s college graduation. The Current Population Survey has collected data on Americans’ educational attainment since 1967 and provides an unparalleled data set for looking at the education level of the population over a broad period of time.

To look more closely at what is happening to education levels of women and men, it helps to look at trends among younger people. Women age 25 to 29 have had higher college attainment rates than men of the same age since 1996. This higher rate is not limited to women in the United States. Nearly all the countries with advanced economies that form the Organisation for Economic Co-operation and Development report that young women are ahead of young men in college completion.

Research on this topic has not given us a clear answer as to why women have overtaken men in college attainment. Traditionally, researchers have looked at levels of education as being driven by the resources available, especially from families, and by the rewards of education, particularly earnings and occupational standing. Most research has concluded that the rewards of education for men and women have not shifted over time in a way that explains women’s higher attainment. 

More information on educational attainment including by race can be found at the U.S. Census Bureau's blog on a "Shift Toward Greater Educational Attainment for Women Began 20 Years Ago."